The proposed investigation seeks new information about the effects of cocaine on brain activity in relation to behavior. An experimental approach using electrophysiological recording, stimulation, and behavioral methods will be applied to study the central nervous system effects of cocaine. Cats and rhesus monkeys chronically prepared with indwelling cortical and subcortical electrodes will serve as subjects. We are especially interested in investigating possible actions of cocaine in modifying excitability of components of the limbic system and related structures. The effects of the drug in altering thresholds for focal afterdischarges to direct stimulation of various limbic structures will be determined. Changes in spontaneous electrophysiological activity and responses to environmental stimuli will be studied using macro- and microelectrode recordings. Attempts will be made to relate changes in brain electrophysiological activity to drug-induced alterations in behavior in subjects trained to respond to environmental stimuli and to direct subcortical stimulation. This series of experiments is designed to provide basic information related to the pathophysiology of cocaine use. More generally, the investigation may also contribute new information about the role of temporal lobe structures during states of vigilance and excitement as well as during the behavioral aberrations and perceptual distortions which may be induced by psychotropic drugs.